This Application is a U.S. National Phase Application of PCT International Application PCT/JP98/02084.
The present invention relates to an apparatus for receiving, recording and reproducing digital video and audio information served through satellite broadcasting, and, more particularly, to a digital signal recording and reproducing apparatus which is compatible with the currently available analog recording method.
At the present, digital satellite broadcasting services have been started in the United States as its beginning in Japan and in Europe. In digital satellite broadcasting of this kind, high picture quality, high sound quality and channel multiplexing have been realized by substantially compressing an amount of information signal containing video signal and audio signal with a digital signal compression technique. Also, decoders for decoding transmitted digital information signals into analog format video signals and audio signals have been spreading rapidly.
At the same time, recording methods of the digital signal such as DVC (Digital Video Cassette), DVHS (Digital VHS), etc. are in progress or practical use, in addition to analog recording methods of the currently existing VHS format, SVHS format, etc. as the home use VTR (Video Tape recorder), so as to realize a recording of the video and audio signals for a long period of time without deterioration. Moreover, specifications of digital interface have also been studied in order to transmit signals at a high speed without deterioration among those digital apparatus, and they are now in a process of standardization with the IEEE standard 1394 (IEEE: The Institute of Electrical and Electronics Engineers, Inc.), for example.
Amid these developments, recordings with a higher picture quality and a longer time than the analog signal recording methods of the prior art have come to a reality with a decoder capable of receiving digital satellite broadcastings and a VTR of a digital signal recording method connected via a digital interface.
One example of connecting such digital apparatus of the prior art is shown in FIG. 4.
In FIG. 4, a decoder 35 receives a digital satellite broadcasting, and decodes it into analog video/audio signal. A VTR 36 is a recording and reproducing apparatus for recording and reproducing analog video/audio signals, e.g., analog signals in the VHS format, etc., fed in through an input terminal 40, and also recording and reproducing digital signals, e.g., digital signals in the DVHS format, etc., fed in through an input/output terminal 41. A TV monitor 11 is a monitor for displaying images and producing sounds by inputting analog video/audio signals output from the decoder 35 and analog video/audio signals output from the VTR 36, and it has two input terminals 43 and 44.
The decoder 35 is provided with an input terminal 37, an output terminal 38 and an input/output terminal 39. The input terminal 37 inputs received digital video/audio signals, and the output terminal 38 outputs decoded analog video/audio signals. Also, the input/output terminal 39 is a digital interface terminal for the decoder 35 to exchange digital signals with other apparatus.
In the VTR 36, the external input terminal 40 is for inputting analog video/audio signals, an output terminal 42 is for outputting reproduced analog video/audio signals, and the input/output terminal 41 is a terminal for digital interface.
An output signal of the decoder 35 is fed to the first input terminal 43 of the TV monitor 11, and an output signal of the VTR 36 is input to the second input terminal 44 of the TV monitor 11. In viewing images and sounds by receiving a digital broadcasting program, the TV monitor 11 inputs analog video/audio signals from the output terminal 38 via the input terminal 43, and outputs images and sounds of the program.
Also, when recording a particular information received and selected among digital broadcasting programs, the VTR 36 records digital signals of the images and sounds with a digital signal recording method by connecting the decoder 35 and the VTR 36 with a cable for the digital interface. When reproducing digitally recorded signals, the decoder 35 reads the digital signals from the VTR 36 via the digital interface, decodes them into analog video/audio signals within the decoder 35, and outputs the analog video/audio signals from the output terminal 38. Then, the TV monitor 11 inputs the output signals through the input terminal 43 of the TV monitor 11, and displays the images and produces the sounds.
Next, when a ground wave broadcasting, etc. is received, analog video/audio signals are input from a tuner (not shown in the figure) via the input terminal 40, and they are recorded in a magnetic tape with an analog signal recording method such as the VHS format. When the magnetic tape, recorded in the analog format as above, is played-back with the VTR 36, the video/audio signals are output from the output terminal 42, they are then fed to the input terminal 44 of the TV monitor 11, and the TV monitor 11 displays the images and produces the sounds.
As described, the TV monitor 11 inputs analog signals from the first input terminal 43, when receiving and viewing a digital broadcasting, and when reproducing and viewing recorded digital video/audio signals with the VTR 36. Also, when reproducing analog video/audio signals recorded in the existing VHS format, etc., the TV monitor 11 inputs the analog signals from the second input terminal 44.
Accordingly, a viewer must switch an input to the monitor, when receiving and viewing a digital broadcasting, and when reproducing and viewing recorded digital video/audio signals with the VTR 36, or when reproducing analog video/audio signals recorded in the existing VHS format, etc.
One of the reasons for necessitating two input terminals on the TV monitor is that it is not desirable, in view of concern about a copyright, is to provide a condition allowing a digital signal to be taken out of a decoder in a form of easily decodable digital signal. In other words, a digital signal output from the decoder 35 via the digital interface shall not be an easily decodable digital signal. Hence, the decoder for digital broadcasting must decodes digital information signal it inputs, and outputs it as an analog signal. Also, when utilizing other recording apparatus for digital signals, the digital signals shall not be easily decodable signals.
For the above reason, if a decoder for digital broadcasting and a VTR for digital broadcasting having a compatibility with the existing analog recording method are composed separately, an input for the TV monitor must be switched every time when receiving and viewing a digital broadcasting, and when reproducing and viewing signals recorded with the existing analog recording method such as the VHS format, etc. It is especially annoying for an elderly viewer not familiar with manipulation of the audio/video apparatus to switch a source of audio/video signals by using a selector. Moreover, the viewer is afflicted even more with this problem, if the TV monitor is equipped only with one input terminal. Therefore, it is desirable to make audio/video apparatus capable of outputting a program, which is determined as what is desired to watch, to a TV monitor without requiring a switching manipulation.
The present invention is derived in consideration of the above-described problem of the prior art, and it aims at realizing a digital signal recording and reproducing apparatus, which is capable of providing an enjoyment of receiving new services of the digital broadcasting without necessitating to switch an input of a TV monitor, and viewing and listening to images and sounds that is recorded with the existing analog recording method such as the VHS format.
Although the VTR 36 records a signal fed through the input terminal 40 in the analog format, an input of the TV monitor 11 must be switched, even when it digitally records input analog video/audio signals by compressing them such as with the DVC. While the VHS format has been described as an analog recording method, a switching manipulation is also necessary in the same manner even with other analog recording methods such as the SVHS format, the xcex2 format, etc.
A digital signal recording and reproducing apparatus of the present invention has a digital information decoding circuit for outputting (a) a digital information signal of a channel selected among those received, and (b) a first analog signal by selecting and decoding one of a selected digital information signal, and a reproduced digital information signal of a recording medium. A recording and reproducing unit is provided for outputting a reproduced digital signal, and includes (a) a digital signal recording unit for inputting a digital information signal of the channel selected and output by the digital information decoding circuit, and for recording on a recording medium, (b) a digital signal reproduction unit for reproducing the digital signal recorded on the recording medium, and (c) a first recording and reproduction unit for recording and reproducing an externally input analog video/audio signal on the recording medium as a second analog signal. Over a bus line is transmitted (a) the digital information signal of the channel selected and output by the digital information decoding circuit to the recording and reproducing unit, and (b) the digital information signal output by the recording and reproducing unit to the digital information decoding circuit. An analog information selecting circuit selects and outputs either one of (a) the first analog signal decoded by the digital information decoding circuit, and (b) the second analog signal reproduced by the recording and reproducing unit.